One major factor behind the drop in WTI and Brent crude futures prices has been higher U.S. oil inventories. Perhaps exacerbating this fundamental pressure has been the fact that, ahead of pre-driving-season demand, certain speculators have sold their oil market positions.

OPIS is also keeping a close eye on geopolitics as a motivator for oil price volatility, with announcements from the Trump administration on Iranian sanctions and breaking news out of Venezuela particularly in-focus.

How Gasoline and Diesel Prices are Trending Ahead of Memorial Day

Turning to gasoline and distillate markets, refinery operations are still limping along. Total refinery utilization from the EIA to start the month of May was less than some 90% -- a little bit lower than where it might usually be this time of year.

We saw a bit of a spike in downtime at Midwest refineries due to planned and unplanned issues, which should make gasoline and distillate supplies relatively tight. It could also help build up Cushing inventories as refiners take in less crude oil.

But by the end of May, just in time for Memorial Day, we're expecting U.S. refineries to be largely clicking on all cylinders.

Moving from the refinery gate to the gas pump, U.S. retail gasoline prices were just below $2.90 a gallon. There’s probably a little bit more upside. But for the most part, OPIS analysts think most of the big moves have been made.

The recent drop in oil and refined products prices, however, should give fuel marketers a little bit of profit margin relief after two months of pinch.

California retail gas prices were still above $4 a gallon, mostly due to refinery issues there. We've seen imports come in to help support supplies there and OPIS expects that to continue as high prices pull cargos from other regions that can make California-spec gasoline.

Tip: That chart Denton showed is the kind of information you see in the OPIS Refinery Maintenance Report, a real-time report listing planned and unplanned U.S. refinery maintenance, which impact refined product supplies.